Fourth branchial pouch sinus: Diagnosis and treatment RICHARD M. ROSENFELD, MD, and HUGH F.BILLER, MD, Pittsburgh. Pennsylvania, and New York, New York The fourth branchial pouch sinus (FBPS) Is a rare translaryngeal anomaly with diverse manifestations. Including neonatal stridor and recurrent deep neck Infection. Review of the world literature reveals 23 reports of sinuses consistent with fourth pouch origin. We present two additional cases, Including the only example of a right-sided FBPS. Retrograde excision, beginning at the piriform apex, ensurescomplete removal of the tract and protection of the recurrent nerve. Theposterior border of the thyroid ala must be resected or retracted for adequate exposure. Failure to remove the translaryngeal portion of the tract almost guarantees recurrence. (OTOLARYNGOL HEAD NECK SURG 1991; 105:44,) METHODS The branchial pouches of the primitive pharynx are the endodermal companions to the four ectodermal clefts first noted in the human embryo by Von Baer in 1827. I After penetrating the surrounding mesoderm, the elongated pharyngobranchial ducts of the third and fourth pouches quickly lose their pharyngeal connections." Incomplete obliteration results in a vestigial sinus of the piriform fossa. with a predictable origin and course determined by the fixed mesodermal derivatives of adjacent arches.' Clinical experience suggests that persistence of the fourth pouch is a rare, but well-defined, clinical entity that offers conceptual, diagnostic, and therapeutic challenges not encountered with anomalies of more rostral arches."!' Review of the "branchial" literature, however, reveals that a great deal of confusion sHU exists regarding sinuses of the third, and especially the fourth branchial pouches. The purpose of this article is to present a lucid description of the fourth branchial pouch sinus (FBPS) on the basis of surgical experience with two patients, and a review of the world literature and pertinent embryology. Distinguishing features from the more common second and third arch anomalies are discussed. The value of developmental anatomy as a surgical "road-map" in a potentially amorphous mass of postinflammatory fibrosis is emphasized. From the Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh (Or. Rosenfeld), and the Department of 010laryngology, Mount Sinai Medical Center (Or. Biller). Presented at the Annual Meeting of the Triological Society. New Haven, Conn., Jan. 26-27, 1990. Received for publication May 14, 1990; accepted Feb. II. 1991. Reprint requests: Richard M. Rosenfeld. MD, Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh. 3705 Fifth Avenue. Pittsburgh. PA 15213-2583. • 2311128883 The distinction between sinuses of the third and fourth branchial pouches is not possible using clinical and/or radiographic criteria because both sinuses originate from the piriform fossa and have similar clinical presentations, Consequently, only surgically explored sinuses reported in sufficient detail to be suggestive of fourth pouch origin have been included in this review (Tables I and 2). Possible remnants of the fourth branchial cleft, lacking a piriform connection, have been reported by Downey and Ward l 4 and Shugar and Healy" and will not be considered in this review. Among these 23 patients are eight classified by Miyauchi et al." as third pouch sinuses, despite surgical findings consistent with a diagnosis of FBPS. The authors base their diagnosis on the observations that the superior parathyroid gland (pouch 4) was consistently unrelated to the observed sinus, and some patients had ectopic thymus (pouch 3) adjacent to the tract; however, pharyngobranchial duct remnants do not necessarily involve their respective parathyroids, and thymic tissue may originate from the fourth pouch. 16 Because remnants of third and fourth pouch glandular structures, as well as thyroid tissue, have been reported in relation to the FBPS tract, 12 histologic findings should be viewed with caution as indicators of arch derivation. CASE REPORTS Case 1, A 31/2-year-old boy had a I-year history of recurrent acute suppurative thyroiditis. Incision and drainage suggested a pharyngeal connection, because liquids subsequently dribbled from the site during meals. Barium swallow revealed a slender sinus originating from the right piriform apex (Fig. I), and a diagnosis of third or fourth pouch sinus was entertained. Surgical explorationdemonstrateda fistulacommencingat the anterior border of the midportion of the sternomastoid Volume 105 Number 1 July Fourth branchial pouch sinus: Diagnosis and treatment 1991 lablei. a Criteria for diagnosis of fourth branchial pouch sinus Orlgln Course Termination Connection with piriform fossa must be demonstrated by radiography. endoscopy. or surgical exploration Surgery must reveal tract which descends from piriform passIng caudal to SLN and rostal to RLN Physical examination, radiography or surgery must show tract ending as a blind sinus. cyst. abscess. or fistula within or adjacent to superior pole of thyroid gland SLN. Superior laryngeal nerve; RLN. recurrent laryngeal nerve. lable 2. Surgically explored piriform apex sinuses consistent with a diagnosis of fourth branchial pouch sinus Patient no. Sex 1 2 M 3 ? 4 5 M 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 F F SouIce lyear) Sandborn' (1972) Tucker and Skolnick" (1973) Roediger et al.? (1977) 9 mo/2 mo 5 yr/6 mo Andrieu-Guitrancourt et al.'o (1979) 30 d/30 d M F F Mlyauchi et al.9 (1981) F F M F M F F M F M M M F F F M M Age at dlagnosls/on..t IYI/mo/d) Burge 3 (1983) Ostfeld et al.' (1985) Tovi et al.8 (1985) Kartheuser et al.6 (1986) Tanyel et al." (1986) Andrieu-Guitrancourt et al.'2 (1988) Rosenfeld and Biller (1989) 3 d/3 d Birth/Birth Birth/Birth 6 yr/6 yr 18yr/6yr 17 yr/10 yr 7 yr/7 yr 12 yr/4 yr B yr/B yr 13 yr/8 yr 50 yr/l0 yr 55 yr/7 yr 6mo/Birth 15 yr/13 yr 1 yr/? 9 yr/1 yr 7 mol? 17 yr/17 yr 14 yr/? 21 yrl 18 yr 3 yr/2 yr 17 yr/14 yr Side; presentation No. ot I.D/exclalon L-LNC; hoarseness L-LNA, recurrent 0/1 1/1 L-LNC; impending respiratory distress L-LNA; cyanosis L-LNC; impending respiratory distress L-LNC; stridor L-AST, recurrent L-AST, recurrent L-AST. recurrent L-AST, recurrent L-AST, recurrent L-AST, recurrent L-AST. recurrent L-AST, recurrent L-AST. recurrent L-LNC; stridor L-LNA, recurrent L-AST, recurrent; PCF L-LNA, recurrent L-LNA; PCF L-AST L-AST, recurrent L-AST, recurrent R-AST, recurrent; PCF L-LNC, recurrent; PCF 0/2 3/3 1/2 0/1 1/3 All patients had between one and ten episdoes before referral for treatment 1/1 1 11 2/1 2/2 1/1 Oil 3/2 0/2 2/2 L, Left; R, right; LNC, lateral neckcyst; LNA, lateral neckabscess; AST, acute suppurative thyroiditis; PCF, pharyngocutaneous fistula; 1&0. incision and drainage. Table 3. Mesodermal - derivatives of the branchial arches Thirdarch Fourth arch Sixth arch Glossopharyngeal nerve Hyoid body and greater cornu Common carotid artery Proximal internal carotid artery Superior constrictor muscle Superior laryngeal nerve Thyroid cartilage Aortic arch Right subclavian artery Inferior constrictor muscle Recurrent laryngeal nerve Cricoid and arytenoid cartilages Ductus arteriosus Intrinsic laryngeal muscles 46 otolaryngologvHead and Neck Surgery ROSENFELD and BILLER Fig. 1. Barium swallow demonstrating slender sinus orig inating from the right p iriform apex (arrow) . muscle. adherent to the superior pole of the thyroid gland . The tract entered the larynx after passing under the inferior constrictor muscle near the cricothyroid joint. Postinflammatory fibrosis prevented ident ification of the recurrent laryngeal nerve (RLN); hence. the tract was ligated cxtralaryngeal and the procedure terminated . Histology showed a squamous-lined cyst and tract . and a diagnosis of fourth branchial pouch sinus was made . Recurrent deep neck abscess after 2 month s neces sitated re-exploration. A 3- x 3-cm abscess cav ity was encountered adherent to the ala of the thyroid cartilage . Separation of the cricothyroid joint and excision of a I-em strip of posterior thyroid ala ( Fig. 2) revealed a tract originating from the pirifonn apex. extending caud ally for 2 em. then turning lateral to exit the larynx at the cricothyroid joint (Fig . 3). The tract was ligated at its piriform origin. inferior to the superior laryngeal nerve (SLN) . and excised. Identification of the RLN was not possible becau se of extensive scarring . Histolog y showed a squamous-lined tract with islands o f ectopic thyroid tissue . Case 2. A 17-year-old boy had a 3-year history of recurrent anterolateral left neck cyst and fistula. of presumed thyroglossal origin. Three earlier attempts at exc ision were unsuccessful. A pharyngeal connection was evident from the appearance of liquids in the neck immediately after drinking . Barium swallow revealed a left piriform apex sinus tract. Exploration demonstrated a fistula commencing anterior to the lower third of the sternomastoid muscle . passing medial to the carot id sheath toward the cricothyroid joint. superfi cial to the RLN . A Woodman approach with disarticulation of the cricothyroid joint and anterior retraction of the thyroid ala exposed the origin from the piriform apex. inferior to the SLN . The 6-cm tract was completely exci sed . with pursestring clo sure of the pharyngeal defect. Histology revealed a squamous lining . DISCUSSION Fundamental to an under standing of the fourth bran chial pouch anomaly is a clear distinction between the terms cyst. sinus. and fi stula. Cysts may occur independently. or in association with a sinus or fistula. A sinus is a tract that maintains a connection with either the skin (branchial cleft sinus) or the pharynx (branchial pouch sinus). " Generally. the branchial cleft sinus is associated with rostral arches (first and second). and the branchial pouch sinus with caudal arches (third and fourth). Intermediate arche s (second and third) can also form fistulae. or tracts joining the pharynx and skin. A true fistula of the fourth arch. although theoretically possible. would follow an extremely tortuous course. and has never been reported. A pseudo-fistula. however. may develop after iatrogenic or spontaneous rupture Volume 105 Number 1 July 1991 Fourth branchial pouch sinus: Diagnosis and treatment 47 Fig. 2. Cyst cavi1y and the extralaryngeal portion of the tract have been removed to expose the thyroid ala and cricothyroid joint. Arrow indicates position at which tract entered larynx; arrowheads point to proposed thyroid cartilage cut. of a cervical abscess caused by a branchial pouch sinus. Branchial pouch sinuses may arise from the second through fourth arches (Fig. 4); the first pouch persists as the tubotympanic recess, and the rudimentary sixth POuch-actually an appendage of the fourth-lacks an independent pharyngeal connection.' The origin of the seCond pouch sinus from the tonsillar fossa, and its course between the internal and external carotid arteries, is well-known to clinicians from its frequent occurrence as the internal component of the second arch fistula. Less commonly appreciated is the ability of an isolated second pouch sinus to cause recurrent unilateral tonsillitis and parapharyngeal abscesses." Confusion regarding the third and fourth pouch sinuses stems from their common piriform fossa origin and similar clinical presentations as neck or thyroid abscesses.':" Distinction, however, is of more than academic interest because of the unique surgical approach required for the fourth pouch sinus. A third branchial pouch sinus must pass between mesodermal derivatives of the third and fourth arches (Table 3). Thus the tract would exit from the rostral aspect of the piriform sinus, pierce the thyrohyoid membrane cranial to the SLN and inferior constrictor, then descend between the common carotid artery and vagus nerve, ending lateral to the thyroid gland." Likewise, a sinus from the fourth pouch must pass between fourth and sixth arch structures (there is no fifth arch in human beings). After originating near the piriform apex, cau- 41 ROSENFELD and BillER OtolaryngologyHead and Neck Surgery FIg. 3. Removal of posterior aspect of thyroid cartilage clearly reveals tract origin from piriform apex. below superior laryngeal nerve. Arrows indicates facet of cricothyroid joint; arrowhead shows cut edge of thyroid 010. dal to the SLN, the tract would descend translaryngeal under the thyroid ala to emerge beneath the inferior constrictor muscle, and exit the larynx near the cricothyroid joint. Descending superficial to the RLN. the tract would terminate paratracheal, or within the thyroid gland (Fig . 5).12.21 Table 2 shows that the FBPS is a unilateral disorder with a slight female predominance, reported in patient s from birth to 55 years, with onset of symptoms occurring before age 20 years (mean age , 6 years). This contrasts with the traditional description of branchial sinuses, as almost always seen at or shortly after birth and occurring bilaterally in up to one third of those affected. 14 In some patients, the FBPS appears capable of remaining quiescent for years, or even decades , despite initial episodes in childhood or adolescence (patients 14 and 15). All patients , except one (patient 24) , had a left-sided sinus. Possible explanations include diminished or absent growth of the right ultimobranchial body/ the ob- servation of a similar left-sided predominance of congenital thymic anomalies;" and the asymmetric development offourth arch vascular structures . 12 Conversely, right-sided sinuses may simply demonstrate a greater propen sity to remain asymptomatic . Two clinical presentations are apparent from an examination of Table I. The first consists of neonates with a lateral neck cyst or abscess associated with actual, or impending, airway compromise (patients 3 through 6 and 16). The mass mimics a cystic hygroma. and may contain air or increase in size during crying or Valsalva . A second presentation is that of a child. adolescent. or occasionally an adult, with recurrent infections of the neck or thyroid gland. All patients have a demonstrable internal sinus tract originating at the piriform apex; a pharyngocutaneous fistula is not uncommonly seen after external drainage, either spontaneous or surgical, of an acutely infected sinus (patients 18,20,24, and 25). Complete surgical excision of the tract, including its Volume 105 Number 1 July 1991 Fourth branchial pouch sinus: Diagnos is and treatment 49 4 th POU CH UN --4r.~ Fig. 5. Posterior-oblique view demonstrates translaryngeal c ourse of fourth bran c hial pouch sinus. Forclar i1y. piriform fossa ha s been rem oved . except for a po rtion of the apex . Position of tract corresponds to embryologic descent of parathyroid N via phoryngobronchiol duct. Fig . 4 . Comparison of the origin and course of vestigial sinuses of the second. third. and fourth b ranch ial pouches. piriform attachment. is the most effective treatment of the FBPS. This is possible only if the disorder is suspected preoperatively and appropriate exposure of the piriform fossa is planned: partial excision carries a high risk of recurrence (see case I). Every patient matching one of the two clinical presentations described earlier should have an active search for a piriform apex sinus tract before surgery. If a barium swallow or sinogram is nondiagnostic. direct hypopharyngoscopy should be performed at the time of surgical excision. When direct examination fails to reveal an obvious sinus. gentle external pressure on the neck may produce a reflu x of pus or fluid into the piriform. Because all patients reviewed had a sinus demonstrated by one of these methods. the failure to demonstrate a sinus argues strongly against the diagnosis of FBPS. Acutely infected sinuses are best treated with antibiotics. and incision and drainage if necessary. Definitive excision should be delayed for several weeks. until inflammation has completely resolved. A surgical approach beginning with exposure of the thyroid ala and carotid sheath allows the operation to commence in a region relatively free of postinflammatory fibrosis. and permits immediate distinction between branchial pouch sinuses of the third and fourth arches. If a tract is dis- 10 ROS£NFEl.D and BUER covered exiting from the thyrohyoid membrane, superior to the SLN, passing between the vagus and common carotid artery. the diagnosis of third pouch sinus is confirmed, and exposure of the piriform fossa is not required. Absence of a tract or fibrosis in this region suggests a FBPS, and the piriform apex must be exposed by a Woodman approach," or preferably by excision of a vertical strip of posterior thyroid ala ( Fig. 3) after first disarticulating the cricothyroid joint. The FBPS tract is ligated from the piriform and any pharyngeal defect repaired with purse-string closure. Retrograde excision is then performed, ending with a surrounding ellipse of skin if a fistula was present. A portion of the superior pole of the thyroid gland may be included if necessary; the superior parathyroid should be preserved. If the tract descends paratracheal, exposure of the RLN is necessary to prevent injury (a transient postoperative vocal cord paralysis developed in patient 3). When scarring or inflammation prevent adequate identification of the RLN, the excision should terminate at the cricothyroid region to prevent accidental nerve injury. Once the piriform connection is completely severed, there appears little tendency for recurrence. CONCWlIONI 1. The FBPS is a well-defined clinical entity that must be considered in the differential diagnosis of neonatal respiratory distress, and recurrent deep neck infection in children and adults. 2. All patients have a demonstrable internal sinus from the piriform apex by contrast radiography or endoscopy. Surgical exploration is necessary to distinguish a FBPS from the more common sinus of the third pouch. 3. Excision is best performed retrograde, beginning with complete exposure of the piriform fossa; removal of only the extralaryngeal portion of the tract almost guarantees recurrence. 4. A high index of suspicion, combined with a thorough understanding of the developmental anatomy of the branchial region, should lead to earlier detection and more effective treatment. REFERENCES I. Meyer HW. Congenital cysts and fistulae of the neck. Ann Surg 1932;95: 1-26. 226-48. OtolaryngologyHead and Neck SUrgery 2. Davies J. Embryology and anatomy of the head, neck, face, palate, nose, and paranasal sinuses. In: Paparella MM, Shumrick. DA, eds. Otolaryngology. Philadelphia: WB Saunders Co., 1980: (Part I) 63-123. 3. Burge D. Middle ton A. 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